Closed Circuit Television (CCTV) is an application which allows a person to view on a television set a camera feed from a nearby location, typically from inside a building this person is located in. CCTV is for example used by residents of a Multi-Dwelling Unit (MDU), such as a condominium or apartment building, to view an internal camera feed provided by one or multiple security cameras at the building entrance allowing the residence to view visitors before letting them in. CCTV systems are also used for security purposes in commercial or professional buildings where the CCTV feed is typically monitored by security personnel or an automated system.
In most residential and some commercial applications, CCTV signals are provided through television channels. Cable companies providing an analog television service to customers living in MDUs often offer to integrate the local CCTV signal in their own cable feed. This is usually accomplished by filtering the incoming cable television signal to remove one channel therefrom and substituting in its place the properly modulated CCTV signal before distribution to the subscribing unit of the MDU. However, when dealing with fully digital TV, this approach cannot be used, as the incoming digital signal is only decoded at the set top box in each subscribing unit. In order to properly encode the CCTV signal and integrate it in the regular digital television feed, the approach previously employed has been to send the local, unencoded CCTV signal from the MDUs to the closest headend, where the CCTV signals from all the subscribing MDUs serviced by the same headend are digitally encoded and multiplexed with the entire broadcasted digital television feed. From there, the resulting television feed is sent to all subscribing customers through various central offices. Although only the units of a particular MDU are allowed to see the CCTV signal from their local camera, the same signal is actually received by every subscriber in a large area, generating an important waste of bandwidth, and making this technique impossible to apply to a large scale.
While CCTV channels are useful, they usually serve only the very limited purpose of identifying visitors at the building entrance. While they need to be constantly operational, they are in fact consulted only sporadically. There is therefore a need for a manner of improving and make more profitable the use of CCTV channels.